This application relates to the art of hydraulic devices and, more particularly, to connections between rods and pistons in hydraulic devices. The invention is particularly applicable for use in connecting a push rod to a slave piston in a vehicle brake booster mechanism and will be particularly described with reference thereto. However, it will be appreciated that the invention has broader aspects and may be used in other hydraulic devices.
One form of vehicle power brake commonly includes a slave hydraulic cylinder connected with a vacuum booster. The slave hydraulic cylinder includes a piston connected with a push rod to which force is applied by the vacuum booster. The connection between the piston and the push rod also serves as a valve for selectively opening or closing a passage through the piston depending upon whether the piston is being pulled by the rod or being pushed thereby. The rod is commonly connected with the piston for limited axial movement as by a pin extending through holes in the piston or rod, and axial slots in the other member. An arrangement of this type requiring the use of separate fasteners makes the connection relatively expensive to manufacture and assemble. Relatively close tolerances in boring the holes and slots is necessary to insure proper operation of the valve.
It would be desirable to have an arrangement for connecting the rod to the piston without requiring the use of any movable parts or separate fasteners.